var t = null;
t = setTimeout(time, 1000); //开始执行		
function time() {
    clearTimeout(t); //清除定时器	
    dt = new Date();
    var y = dt.getYear() + 1900;
    var mm = dt.getMonth() + 1;
    var d = dt.getDate();
    var weekday = ["星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"];
    var day = dt.getDay();
    var h = dt.getHours();
    var m = dt.getMinutes();
    var s = dt.getSeconds();
    if (h < 10) {
        h = "0" + h;
    }
    if (m < 10) {
        m = "0" + m;
    }
    if (s < 10) {
        s = "0" + s;
    }
    document.getElementById("head_time").innerHTML = y + "年" + mm + "月" + d + "日" + weekday[day] + "" + h + ": " + m +
        ": " + s + "";
    t = setTimeout(time, 1000); //设定定时器，循环执行           		
}


function Tv() {
    var tv = document.getElementById("tv");
    if (tv.style.display == "none") {
        tv.style.display = "inline"
    } else {
        tv.style.display = "none";
    }
}